Method for producing a multifocal corneal surface using intracorneal microscopic lenses

ABSTRACT

A method for correcting vision of an eye, including the steps of separating a portion of the cornea to form first and second internal surfaces in the cornea, and then placing at least one microscopic lens in between the first and second internal surfaces in the cornea, so that the external surface of the cornea is not substantially displaced. In a preferred embodiment, the microscopic lenses can be placed in concentric circles around the main optical axis so that the lenses form multifocal or bifocal vision.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of Ser. No. 09/852,846,filed May 11, 2001, now U.S. Pat. No. 6,589,280, issued Jul. 8, 2003,the entire contents of which are herein incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to implanting microscopic lenses in a livecornea of an eye to help correct the vision in the eye by producing amultifocal corneal surface. More particularly, the present inventionrelates to inserting microscopic lenses under a corneal flap after asurgical procedure, such as LASIK eye surgery, to correct the vision inthe eye by producing a multifocal corneal surface without substantiallydisplacing the external corneal surface.

BACKGROUND OF THE INVENTION

Conventional surgical techniques use ultraviolet light and shortwavelength lasers to modify the shape of the cornea. For example,excimer lasers, such as those described in U.S. Pat. No. 4,840,175 toPeyman, which is incorporated herein by reference, emit pulsedultraviolet radiation, which can be used to decompose or photoablatetissue in the live cornea to reshape the cornea.

Specifically, the Peyman patent discloses the laser surgical techniqueknown as laser in situ keratomycosis (LASIK). In this technique, aportion of the front of the live cornea can be cut away in the form of aflap having a thickness of about 160 microns. This cut portion is movedaway from the live cornea to expose an inner surface of the cornea. Alaser beam is then directed onto the exposed inner surface to ablate adesired amount of the inner surface up to 150–180 microns deep. The cutportion is reattached over the ablated portion of the cornea and assumesa shape conforming to that of the ablated portion. The LASIK procedureis generally sufficient to correct myopia or distance vision. However,in many patients while the LASIK procedure is sufficient to correctdistance vision it does not correct reading vision in patients who arepresbyopic. Presbyopia is a condition which occurs after age 40 in whichthe lens of the eye loses its ability to change focus. When adistinctive object is in sharp focus on the retina, close objects areout of focus or blurred. To bring close objects into focus the lens ofthe eye changes shape to bring these objects into focus. This rapidmovement of the lens occurs without conscience thought through andallows objects to be brought into focus. When the lens of the eye lossesthis ability, reading glasses or bifocal glasses are used. When apatient in their 40's and 50's have laser surgery and achieve correcteddistance vision they still need glasses for reading. There arefrequently 2 pairs needed one for intermediate distance, such as thecomputer and one for close reading vision.

Additional methods for correcting the refractive error in the eyeinclude inserting an implant in between layers of the cornea. Generally,this is achieved using several different methods. The first methodinvolves inserting a ring between layers of the cornea, as described inU.S. Pat. No. 5,405,384 to Silvestrini. Typically, a dissector isinserted in to the cornea to form a channel therein. Once the dissectoris removed, a ring is then inserted into the channel to alter thecurvature of the cornea. In the second method, a flap can be createdsimilarly to the LASIK procedure, described above, and a large lens canbe inserted under the flap to change the shape of the cornea, asdescribed in U.S. Pat. No. 5,919,785 to Peyman and U.S. Pat. No.6,102,946 to Nigam. The third method involves forming a pocket using amechanical instrument, and inserting an implant into the pocket, asdescribed in U.S. Pat. No. 4,655,774 to Choyce. These procedures allinduce a single corneal curvature change and do not correct bothdistance vision and close vision in a bifocal or multifocal manner.

Additionally, even though these existing intracorneal lenses aresomewhat suitable for correcting distant vision disorders, theytypically cause the eye to experience an undesirable side effectcommonly referred to as a “halo effect”, which is a ring of light that aperson will see in the eye having an implanted intracorneal lens. A haloeffect is caused due to light entering into or being refracted by theintracorneal lens at certain angles which creates a glare that is sensedby the retina of the eye and thus experienced by the person.

Although the severity of the halo effect can vary depending on the shapeof the intracorneal lens and the amount of direct and ambient lightbeing received by the eye, the halo effect can cause the patient muchannoyance. Also, in certain instances, the halo effect can alsoadversely affect the patient's ability to read, drive a car and performother routine activities requiring acute vision.

Additionally, many of these conventional techniques require relativelylarge lenses or corneal implants that stretch or expand the cornealsurface to accommodate the intracorneal lens. These large lenses canlead to corneal erosion, which is generally caused by corneal cellsdying since the lens does not allow nutrients to flow through portionsof the cornea.

Accordingly, a need exists for intracorneal lenses, which can helpcorrect the vision in the eye without displacing the corneal surface,while simultaneously eliminating or reducing glare and the halo effectdue to light reflecting off of the intracorneal lens.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention is to provide animproved method for correcting the vision of an eye.

Another object of the present invention is to provide a method forcorrecting the vision of an eye by inserting or implanting anintracorneal lens.

Still another object of the present invention is to provide a method forcorrecting the vision of an eye by inserting an intracorneal lens,without the lens substantially altering the shape of the cornea, so thatundue tension is not experienced by the corneal flap.

Yet another object of the present invention is to provide a method forcorrecting the vision of an eye by inserting an intracorneal lens thatchanges the refraction of the eye by having a different refractive indexthan the corneal tissue.

Yet another object of the present invention is to provide a method forcorrecting the vision of an eye using multiple microscopic lenses, sothat glare can be reduced or eliminated.

Yet another object of the present invention is to provide a method forcorrecting the vision of an eye by placing multiple microscopic lensesunder a corneal flap.

Yet another object of the present invention is to provide a method forcorrecting the distance vision and close vision of an eye.

The foregoing objects are basically attained by a method for correctingvision of an eye, the eye having a cornea with an external surface andan optical axis, comprising the steps of separating a portion of thecornea to form first and second internal surfaces, and placing at leastone microscopic lens in between the first and second internal surfaces,so that the external surface of the cornea is not substantiallydisplaced.

Other objects, advantages, and salient features of the present inventionwill become apparent to those skilled in the art from the followingdetailed description, which, taken in conjunction with the annexeddrawings, discloses preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the drawings which form a part of this disclosure:

FIG. 1 is a cross-sectional side view of an eye.

FIG. 2 is a cross-sectional side view of the eye of FIG. 1 with a flapformed thereon.

FIG. 3 is a front elevational view taken along lines 3—3 of FIG. 2.

FIG. 4 is a cross-sectional side view of the eye in FIG. 3 with the flapmoved away from the surface of the cornea and a laser ablating anexposed surface of the cornea.

FIG. 5 is a front elevational view of an eye undergoing a preferredmethod of the present invention, specifically, microscopic lenses areplaced on both the first and second exposed internal corneal surfaces.

FIG. 6 is a cross-sectional side view taken along lines 6—6 of FIG. 5.

FIG. 7 is a cross-sectional side view of the eye of FIG. 6 with the flapreplaced over the exposed surface of the cornea and the microscopiclenses.

FIG. 8 is a front elevational view of an eye undergoing the preferredmethod of the present invention, wherein the microscopic lenses aresubstantially ring-shaped.

FIG. 9 is a front elevational view of a microscopic lens used in themethod described herein.

FIG. 10 is a cross-sectional side view taken along lines 10—10 of FIG.9.

FIG. 11 is a front elevational view of a substantially ring-shapedmicroscopic lens used in the method described herein.

FIG. 12 is a cross-sectional side view taken along lines 12—12 of FIG.11.

FIG. 13 is a front elevational view of an eye undergoing the preferredmethod of the present invention, wherein there is one substantiallyring-shaped lens having a microscopic ring portion.

FIG. 14 is a front elevational view of a substantially ring-shaped lenshaving a microscopic ring portion used in the method described herein.

FIG. 15 is a cross-sectional side view taken along lines 15—15 of FIG.14.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As seen in FIGS. 1–7, the refractive properties of eye 10 can be alteredby creating a corneal flap 12 in the cornea 14, ablating the cornea toreshape the cornea and the external surface 15 of the cornea, and thenplacing multiple microscopic lenses or inlays 16 under flap 12.

To begin, the refractive error in the eye is measured using wavefronttechnology, or any other measurement device desired, as is known to oneof ordinary skill in the art. For a more complete description ofwavefront technology see U.S. Pat. No. 6,086,204 to Magnate, the entirecontents of which is incorporated herein by reference. The refractiveerror measurements are then used to determine the proper correctionnecessary. For example, the information from the wavefront technologydetermines the proper portions of the cornea of the eye to be ablated,if necessary, and the proper power of the lenses 16 and/or the number ofthe lenses 16 to be implanted.

As seen in FIGS. 2 and 3, flap 12 is created on the surface of thecornea by using a tool or device (not shown) that is known to oneskilled in the art, such as a microkeratome. The device separates thecornea and exposes a first surface 18 and a second surface 20. The firstsurface 18 faces in an anterior direction and the second surface 20faces in a posterior direction of the eye. The flap is moved to exposesecond surface 20 using a spatula, forceps or any other device desired.The flap 12 is preferably coupled or connected to the cornea by aportion 22 that allows the flap to be moved away from or pealed fromsurface 18 in a hinged manner, as seen specifically in FIGS. 4–6 and 8.However, the flap does not necessarily need to be coupled to the corneain a hinged manner and can be fully removed from the cornea or a pocketcan be formed underneath the external surface of the cornea, with anincision allowing access to the pocket.

If the refractive error of the cornea requires correcting for distancevision, such as myopia, the LASIK procedure or any other technique knownin the art can be preformed. Preferably, LASIK, as disclosed in U.S.Pat. No. 4,840,175 to Peyman and is known to one of ordinary skill inthe art, is used and preferably a portion 30 of surface 18 and surface20 of the cornea under corneal flap 12 is ablated using an excimer laser32 to achieve the proper corrective vision for distances, as seen inFIG. 4. However, a portion of surface 20 can be ablated or a portion ofboth surfaces 18 and 20 can be ablated. If no distance vision correctionis required, it is not necessary to perform the LASIK procedure or anyother distance corrective procedure known in the art.

Furthermore, as shown in FIG. 13, microscopic lens 16″ can be asubstantially ring shaped lens with an arcuate cross section and firstand second surfaces 24″ and 26″, as seen in FIGS. 14 and 15. Lens 16″has an outside wall or surface 33 and inside wall or surface 34 thathave diameters that are sufficiently large enough to encircle the mainoptical axis of the eye 28 with the center of the ring, aligned with themain optical axis. In other words, the diameter of wall 32 is preferablyabout 3–5 millimeters, but can be any size desired. However, thedistance or ring portion 36 between wall 33 and wall 34 and thethickness of lens 16″ is preferably microscopic. As described above,microscopic as defined herein means preferably that distance 36 is about1 millimeter and the thickness of lens 16″ is about 1–50 microns thick,and more preferably, distance 36 is less than about 1 millimeter andlens 16″ is about 2–3 microns thick. Preferably, multiple rings 16″ areplaced under the flap, as shown in FIG. 13. The lenses are placed orpositioned in concentric circles of about 3, 4 and/or 5 millimetersaround the main optical axis, each having a different refractive power,thus allowing multifocal vision. However, any number of lenses can beplaced around the main optical axis and, including only one or anynumber greater than one, and the lenses may each have the samerefractive power or any combination of the same or different refractivepower. In other words, two lenses can have the same refractive power andone lens can have a different refractive power.

Furthermore, as shown in FIG. 13, microscopic lens 16″ can be asubstantially ring shaped lens with an arcuate cross section and firstand second surfaces 24″ and 26″, as seen in FIGS. 14 and 15. Lens 16″has an outside wall or surface 32 and inside wall or surface 34 thathave diameters that are sufficiently large enough to encircle the mainoptical axis of the eye 28 with the center of the ring, aligned with themain optical axis. In other words, the diameter of wall 32 is preferablyabout 3–5 millimeters, but can be any size desired. However, thedistance or ring portion 36 between wall 32 and wall 34 and thethickness of lens 16″ is preferably microscopic. As described above,microscopic as defined herein means preferably that distance 36 is aboutone millimeter and the thickness of lens 16″ is about 1–50 micronsthick, and more preferably, distance 36 is less than about onemillimeter and lens 16″ is about 2–3 microns thick. Preferably, multiplerings 16″ are placed under the flap, as shown in FIG. 13. The lenses areplaced or positioned in concentric circles of about 3, 4 and/or 5millimeters around the main optical axis, each having a differentrefractive power, thus allowing multifocal vision. However, any numberof lenses can be placed around the main optical axis and, including onlyone or any number greater than one, and the lenses may each have thesame refractive power or any combination of the same or differentrefractive power. In other words, two lenses can have the samerefractive power and one lens can have a different refractive power.

Lenses 16, 16′ and 16″ are preferably formed of any polymer or syntheticmaterial desired, such as plastic, glass, silicon, methametacolade, orany acrylic that preferably has a refractive index that is differentfrom the refractive index of the cornea. However, the lenses may be anymaterial desired that would help correct the refractive error in thecornea.

Preferably, second surface 26 of at least one microscopic lens 16 isplaced on the first corneal surface 18 of cornea 14. However, firstsurface 24 may be placed on second corneal surface 20 or any combinationthereof when multiple lenses are used. For example, first surface 24 ofat least one lens can be placed on corneal surface 20, while secondsurface 26 of at least one lens can be placed on corneal surface 18.

More preferably, when lenses 16 and 16′ are used, about 50 microscopiclenses are placed in between the first and second surfaces 18 and 20;however, any number of lenses desired to correct the refractive error inthe cornea can be placed in between the first and second surfaces 18 and20. Depending on the power of the lenses, by inserting the lenses inthis manner an eye will be able to see with either bifocal or multifocalvision. For example, about 50 lenses, each having the same power can beplaced in concentric circles about the main optical axis 28 of the eye.This pattern would allow the patient to view distance vision using theportion of the eye that has no microscopic lenses, while the portionsthat had microscopic lenses would allow a patient to view objects close,such as for the purpose of reading. Additionally, different power lensescan be implanted that would allow multifocal vision. For example, onearray of about 20 plus 1.5 diopter lenses can be placed in the eye inany manner desired (i.e. a concentric circle), while a second array ofabout 20 plus 2 diopter lenses can also be placed in the eye in anymanner desired (i.e. a concentric circle). Furthermore, when using lens16″, multiple lenses can be used in concentric circles, each lens havingeither the same refractive index as each other lens, or a differentrefractive index or any combination thereof that would allow bifocal ormultifocal vision as described above. This allows several differentfocusing points for the eye, allowing the patient to see a variety ofnear and far distances.

As seen in FIG. 7, once the lens or lenses are in place, the flap isreplaced or repositioned on the cornea. Preferably, surface 20 is placedback over surface 18, in the same position prior to removing flap 12.The flap is then sutured or reattached to the cornea in any mannerdesired or simply replaced and allowed to heal.

Since each of the lenses 16 are preferably less than about 2–3 micronsthick, the first corneal surface 18 is not substantially displaced awayfrom second corneal surface 20. In other words, the exterior surface ofthe cornea has approximately the same curvature as the eye originallyhas or has after the distance correcting procedure. This allows littleor no tension to be exerted over the flap 12 when it is reattached andallows for a relatively precise fit of surface 18 and surface 20.

Additionally, the lenses 16 allow for bifocal and multifocal vision byfocusing the light passing therethrough on a different portion of theretina, since the refractive power of each lens is different from therefractive power of the cornea. Therefore, once it is known whatrefractive error is in the cornea and the eye, the only values to bedetermined are whether distance correction is necessary, the power ofthe lenses, or the powers of the lenses for multifocal purposes, and thenumber of lenses.

The implantation of microscopic lenses 16 allow vision correction, whilebeing small enough so as to not produce significant glare refracted fromthe lenses or substantially displace the surface of the cornea or theflap 12. This procedure improves vision without discomforting glareproblems or the undue stress on the cornea experienced by the prior art.

Any discussion of lens 16 and sides 24 and 26 applies to lenses 16′ and16″ and to sides 24′, 24″, 26′ and 26″.

While preferred embodiments have been chosen to illustrate theinvention, it will be understood by those skilled in the art thatvarious changes and modifications can be made therein without departingfrom the scope of the invention as defined in the appended claims.

1. A method for correcting vision in an eye, the eye having a corneawith an external surface and an optical axis, comprising the steps ofseparating a portion of the cornea to form first and second internalsurfaces, placing a first lens having a first opening therein betweenthe first and second internal surfaces, the first opening beingsubstantially centered about the optical axis, the first lens having afirst inner wall defined by the first opening, a first outer wall, and athickness between about one and about 50 microns, and placing a secondlens having a second opening therein between the first and secondinternal surfaces, the second opening being substantially centered aboutthe optical axis and concentric with the first lens, the second lenshaving a second inner wall defined by the second opening, a second outerwall and a thickness between about one and about 50 microns.
 2. A methodaccording to claim 1, wherein the placing step includes placing at leastone of the first and second lenses substantially concentrically aboutthe optical axis of the eye.
 3. A method according to claim 1, whereinthe placing step includes placing both the first and second lensessubstantially concentrically about the optical axis of the eye.
 4. Amethod according to claim 1, wherein the first and second lenses have athickness of about 2–3 microns, so that when the first and second lensesare inserted between the first and second internal surfaces, the firstand second internal surfaces are not substantially displaced.
 5. Amethod according to claim 4, wherein the separating step includesseparating the portion of the cornea to form a corneal flap.
 6. A methodaccording to claim 5, further including the steps of moving the cornealflap to expose the first and second internal surfaces, and replacing thecorneal flap after the first and second lenses have been placed inbetween the first and second internal surfaces.
 7. A method according toclaim 6, wherein the first and second lenses each have a power of aboutplus one to about plus three diopters.
 8. An intracorneal lens systemfor implantation in the eye to correct refractive error thereof,comprising: a first lens portion having a first outer surface and athickness of between about one and about 50 microns, said first outersurface defining a first outer diameter; a first aperture extendingthrough said first lens portion, said first aperture defining a firstinner diameter and a first inner surface; a second lens portion having asecond outer surface and a thickness of between about one and about 50microns, the second outer surface defining a second outer diameter, thesecond lens portion being substantially concentric to the first lensportion; and a second aperture extending through said second lensportion, said second aperture defining a second inner diameter and asecond inner surface; wherein said second lens portion has a refractiveindex different from the refractive index of said first lens portion. 9.An intracorneal lens system according to claim 8, wherein said firstlens portion has a refractive index different from the refractive indexof the cornea.
 10. An intracorneal lens system according to claim 8,wherein said second inner diameter is about one millimeter larger thansaid first outer diameter.